Electronic Circuits and Tutorials
Electronic Schematics - D

Frequency Divider Circuits

Charge-pump circuit divides by two - 02/18/99 Issue of EDN  Small size and efficiency approaching 100% make switched-capacitor charge pumps popular for voltage doubling and inverting in miniature dc-dc applications. Few are aware, however, that most charge pumps can halve as well as double or invert an input voltage. The increasing adoption of low-voltage logic makes this ÷2 capability useful for generating low-voltage supplies in portable.

Cheap 40kHz Clock -  ASCII format.  This circuit has worked for me in many applications. (it might be an idea to buffer the signal befor using it. (There are still 5 unused gates in the 'C14)

Circuit Conditions Variable Duty Cycle Clock -  02/17/97 EDN-Design Ideas.....David Albean, Thomson Consumer Electronics, Indianapolis, INA simple enhancement of an earlier Design Idea ("Delay line implements clock doubler", EDN, July 18, 1996, pg 102) implements a variable-duty-cycle clock-signal conditioner. The circuit accepts an input clock of any duty cycle and generates any desired duty cycle at the output. You need to add only one flip-flop to the earlier design to generate an arbitrary-duty-cycle output. You can use the circuit to correct a non-50% input to a 50% output or to create a non-50% output from any arbitrary input duty cycle.

Circuit divides frequency by N+1 -  11-Jul-02 Issue of EDN  Digital frequency dividers usually use flip-flop stages that connect the Q pin to the D data-input pin of the following stage.  This configuration creates a binary waveform that you can feed back to the input. You can divide any integer lower than 2N with minimal stages, where N is the number of stages.

Circuit forms Divide by 1.5 Counter -  Two inexpensive ICs divide a TTL clock signal by 1.5. By following the circuit with another flip/flop, you could also generate a divide by three function.

Clock divider

Counter Provides Divide by 45 Function - 05/22/97 EDN-Design Ideas..... EDN is migrating links. This link is not verified.  Search the "title" + "EDN" for new link.

Frequency Doubler Operates on Triangle Waves -  03/14/96 EDN-Design Ideas..... EDN is migrating links. This link is not verified.  Search the "title" EDN for new link.

Precision divide-by-two analog attenuator needs no external components -  17-Mar-05 Issue of EDN  Many modern A/D converters offer only a 5V input range, and using these converters with a 65V or larger input signal gives the designer a problem  how to discard half of a good analog signal without introducing errors and distortion. To solve the problem, you can use an attenuator comprising two operational amplifiers and two resistors (Figure 1]..... [Design Idea by Moshe Gerstanhaber and Chau Tran, Analog Devices, Wilmington, MA; Edited by Brad Thompson]

Synthesize Optimal Digital Frequency Dividers -  05/13/99 EDN-Design Ideas.....For many applications, you need to divide a reference clock into one or more sub clocks to use in different parts of the system. Sometimes,.....PDF contains many circuits, scroll to find this one.… [Design Idea by Lindo St Angel, Prairie Comm Inc, Arlington Heights, IL]

Unusual Frequency Dividers

74ACT74 makes low-skew clock divider -  12/17/98 Issue of EDN  Serial-data systems often generate an internal clock at twice the data rate for mid-bit sampling or for generating bi-phase codes. External equipment and some internal processes require a clock that runs at the data rate. Simply dividing the twice-rate clock with a flip-flop generates a data-rate clock that is skewed by one logic delay with respect to the input.  This delay can be a significant fraction of the bit period. You can use specialized PLL-based low-skew divider chips.....Page includes several designs.

Amplifiers perform precision divide by 2 circuit -  6-Mar-03 Issue of EDN  The classic implementation of a voltage-halving circuit uses two equal-value resistors. Using 1% resistors provides a divider output with 2% accuracy. For most applications, this performance is cost-effective andthan adequate. However, when you need extreme precision, this approach requires correspondingly accurate resistors and can become expensive.

Analog divider uses few components -  4-Jan-07 Issue of EDN  Low-cost op amp, CMOS timer perform analog math..... [Design Idea by David Cripe, Chatham, IL; Edited by Brad Thompson and Fran Granville]

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